Telecommunications services provided over an IP Connectivity Access Network (IP-CAN) can be subject to charging and policy control mechanisms. This includes service-aware Quality of Service (QoS) control. Accordingly, some telecommunications systems incorporate Policy and Charging Control (PCC) architectures to provide this control. 3GPP TS 23.203 describes such a PCC architecture in respect of packet flows in an IP-CAN session established by a user terminal through an Evolved 3GPP telecommunications system, including both 3GPP accesses (GERAN/UTRAN/E-UTRAN) and Non-3GPP accesses. FIG. 1 illustrates schematically an example of the PCC architecture described in 3GPP TS 23.203 that comprises a Policy and Charging Enforcement Function (PCEF), a Policy and Charging Rules Function (PCRF), an Application Function (AF), an Online Charging System (OCS), an Offline Charging System (OFCS) and a Subscription Profile Repository (SPR). The architecture can also include a Bearer Binding and Event Reporting Function (BBERF).
The PCRF is a functional element that encompasses policy control decision and flow based charging control functionalities, a combination of the functionality of the Policy Decision Function (PDF) and the Charging Rule Function (CRF) defined in release 6 of the 3GPP specification. A PCRF can be implemented as a standalone node and behaves as a Policy Decision Point (PDP), or Policy Server (PS), that stores user data related to QoS enforcement, access control lists, etc. The PCRF provides policy and charging control for the media components negotiated between the user terminal and the AF. The PCRF receives session and media related information from the AF and informs the AF of traffic plane events. The PCRF also provides network control regarding the service data flow detection, gating, QoS and flow based charging (except credit management) towards the PCEF. The PCRF can provision PCC rules and PCC decisions to the PCEF via a so-called Gx reference point and to the BBERF through a so-called Gxa/Gxc (also referred to as Gxx) reference point. The PCRF also forwards events between the BBERF, the PCEF, and the AF. Criteria such as the QoS subscription information may be used together with policy rules such as service-based, subscription-based, or pre-defined PCRF internal policies to derive the authorized QoS to be enforced for a service data flow. The PCRF PCC decisions may be based on one or more of the following:                information obtained from the AF via a so-called Rx reference point, e.g. the session, media and subscriber related information;        information obtained from the PCEF via the Gx reference point, e.g. IP-CAN bearer attributes, request type, subscriber related information and location information;        information obtained from the SPR via a so-called Sp reference point, e.g. subscriber and service related data;        information pre-defined in the PCRF; and        information obtained from BBERF via the Gxa/Gxc (also referred to as Gxx) reference points.        
The PCEF is a functional entity that behaves as a Policy Enforcing Point (PEP) for enforcing decisions instructed by the PCRF and the OCS. The PCEF provides service data flow detection (based on service data flow filters defined in the PCC rules) to capture and analyse any user and signalling traffic, to identify the user and to capture details of the service(s) being used. The PCEF can then communicate this user and access-specific information to the PCRF over the Gx interface, to the OCS over a so-called Gy interface and to the OFCS over a so-called Gz interface. The PCEF enforces QoS control according to the QoS authorised by the PCRF. The PCEF is preferably co-located within a gateway node implementing the IP access to a Packet Data Network (PDN GW). As such, in a GPRS core network the PCEF is located within a GPRS Gateway Support Node (GGSN), whilst in the case of a CDMA2000 network the PCEF may be located in a Packet Data Serving Node (PDSN), and in a WLAN network the PCEF may be located in a Packet Data Gateway (PDG).
The BBERF supports a subset of the functions provided by the PCEF that includes bearer binding, uplink bearer binding verification and event reporting to the PCRF. Bearer binding is the association of a PCC rule and a QoS rule (if applicable) to an IP CAN bearer within that IP CAN session, and is performed by the Bearer Binding Function (BBF). The BBF is located at the PCEF if GTP is used as the mobility protocol towards the PCEF. Otherwise, where a mobile-IP based protocol, such as MIP, is used instead of GTP, the BBF is located at the BBERF. The QoS rules contain the information from the PCC rules that the BBERF requires to ensure that bearer binding can be performed. The QoS rules therefore contain the SDF template and precedence information, as well as the QoS information (e.g. QCI, bit rates etc). The PCRF provides the BBERF with the QoS rules derived from the PCC rules. The BBERF then enforces the QoS decisions by setting up the appropriate bearers. The Gxx reference point represents the Gxa or Gxc reference points as applicable in each particular context. Gxc applies when the BBERF is located in the S-GW of a 3GPP access, whereas Gxa applies when the BBERF is located in a trusted non-3GPP access.
The AF is an element offering applications that require policy and/or charging control of the IP-CAN user plane behaviour. The AF communicates with the PCRF over the Rx interface to transfer dynamic session information (e.g. a description of the media to be delivered in the transport layer) required for PCRF decisions, as well as to receive IP-CAN specific information and notifications about IP-CAN bearer level events. One example of an AF is the P-CSCF of the IP Multimedia Core Network (IM CN) subsystem. In the case of a P-CSCF, the information communicated over the Rx interface is derived from the P-CSCF session information (e.g. SDP when SIP is used for signalling) and it mainly includes media components. A media component comprises a set of IP flows, each of which is described by a 5-tuple, the media type and required bandwidth. The AF can also subscribe to certain events that occur at the traffic plane level (i.e., events detected by either the PCEF or be BBERF). Those traffic plane events include events such as IP session termination or access technology-type change. When the AF has subscribed to a traffic plane event, the PCRF informs the AF of its occurrence.
The SPR contains all subscriber/subscription related information needed for subscription-based policies and IP-CAN bearer level PCC rules by the PCRF. The Sp interface allows the PCRF to request subscription information related to the IP-CAN transport level policies from the SPR based on a subscriber ID and other IP-CAN session attributes.
The OCS provides authorization for the usage of network resources based on the provisioned data and the user activity information it receives from PCEF. This authorization must be granted by the OCS prior to the actual resource usage. When receiving a network resource usage request, the network assembles the relevant charging information and generates a charging event towards the OCS in real-time. The OCS then returns an appropriate resource usage authorization over the Gy interface. The resource usage authorization may be limited in its scope (e.g. volume of data or duration) therefore this authorization may have to be renewed from time to time as long as the user's resource usage persists. The OCS can support time, volume and event-based charging.
FIG. 2 illustrates schematically the online charging architecture as described in 3GPP TS 32.240. In this architecture, network resource usage requests are sent to a Charging Trigger Function (CTF). The CTF is a mandatory integrated component of all network elements that are involved in online charging. The CTF assembles the relevant charging information and generates an online charging event that is transferred to the Online Charging Function (OCF) within the Online Charging System (OCS) in real-time using a so-called Ro reference point. The OCF then returns an appropriate resource usage authorization based on subscriber account information. This resource usage authorization may be limited in its scope (e.g. volume of data or duration), and may therefore have to be renewed from time to time as long as the subscriber's network resource usage persists. If required by the operator, Charging Data Records (CDRs) may additionally be generated for online charged subscribers. The OCF includes the Session Based Charging Function (SBCF/SCF) and the Event Based Charging Function (EBCF/ECF). The SBCF is responsible for online charging of network/user sessions, e.g. voice calls, IP CAN bearers, IP CAN session or IMS sessions. The EBCF performs event-based online charging (often referred to as “content charging”) in conjunction with any application server or service NE, including SIP application servers.
The introduction of new mobile devices, such as smartphones, that offer advanced capabilities, has lead to an explosion in mobile traffic, as the features of these devices allow users to download and make use of a large variety of applications that have in-turn increased demand for services such as video streaming. The increased use of such data-intensive features is forcing network operators to abandon flat-rate service plans, in favour of subscriptions that charge users based on their network resource usage. In doing so, network operators aim to ensure that the costs of improving their network infrastructures to provide sufficient bandwidth is covered by revenues made from those users that consume it. The current methods of charging users for their network resource usage rely on charging the user based on the volume of data consumed, irrespective of the bandwidth used to transfer the data. As a result, most mobile network operators will apply policies that limit the maximum bandwidth available to users of the network.
It has been recognised here that it would be advantageous to both network operators and users if, at any time, the user could select the bandwidth that they wish to use and be charged according to both the volume of data consumed and the bandwidth used to transfer that data. By way of example, this would allow a user to minimise the cost of their regular network resource usage by choosing a relatively low cost tariff that provides the user with a maximum bandwidth of 100 Kbps. If the same user then wants to download a large file, such as a movie, the user can choose to increase their maximum available bandwidth to 200 Mbps for the duration of the download, with the cost of this network resource usage being determined by a different, comparatively high cost tariff. However, the current charging architectures do not provide mechanisms for implementing such flexible, user interactive policy control and charging.
According to current standards, a PCEF can detect that a user wants to download a particular file, can request that the OCS charge for the downloading of this file at a particular charging rate, and can enforce QoS control so as to allow a particular bandwidth. However, there is no mechanism by which the user can select the bandwidth that is to be used. Nor is there a mechanism that allows the rate at which the downloading of this file is to be charged to be determined based upon the bandwidth provided to the user.
Whilst there are some methods by which limited interactive charging could be implemented, these methods do not provide a mechanism of truly interactive charging. For example, an Advice of Charge (AoC) Function allows users to be aware of an exhausted quota and thus the possibility to recharge the quota, or even to pay an extra fee for a specific item of content that can be obtained using the HTTP protocol. The cost of this extra fee could be varied by the AoC Function by including a token in the URL. The PCEF could then determine the bandwidth to be applied based on that URL. However, this implies that only content from an internal web server, and that can be provided using HTTP, could be charged at a rate that depends on the bandwidth used. Furthermore, this would also require that PCEF be configured with a huge list of URLs and the associated bandwidth that is to be allowed. The burden of initially configuring and maintaining this list makes such an approach infeasible. In addition, such a solution would not allow the user the flexibility to be able to select the bandwidth and charging rate for specific files (e.g. it would be unlikely that a user would be able to download one mp3 file at a particular bandwidth and charging rate, and subsequently download another mp3 with at a different bandwidth and charging rate), and the AoC Function would not be able to charge an extra fee for Internet services (as VoIP calls, P2P, Online TV).